<!DOCTYPE html>
<style>
    .multicol { position:relative; margin-bottom:1px; columns:5; width:20px; column-gap:0; column-fill:auto; height:0; background:red; }
    .multicol > div { height:1px; background:blue; }
</style>
<p>There should be a small blue square below.</p>
<div style="display:flow-root; position:relative;">
    <div class="multicol"><div></div><div></div></div>
    <div class="multicol"><div></div><div></div></div>
    <div class="multicol"><div></div><div></div></div>
    <div class="multicol"><div></div><div></div></div>
    <div class="multicol"><div></div><div></div></div>
    <div class="multicol"><div></div><div></div></div>
    <div class="multicol"><div></div><div></div></div>
    <div class="multicol"><div></div><div></div></div>
</div>
<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
<script>
    test(() => {
        var multicols = document.getElementsByClassName("multicol");
        var offset = 0;
        for (var i = 0; i < multicols.length; i++) {
            var multicol = multicols[i];
            assert_equals(multicol.firstChild.offsetLeft, 0);
            assert_equals(multicol.firstChild.nextSibling.offsetLeft, 4);
            assert_equals(multicol.offsetTop, offset);
            offset++;
        }
    }, "Zero-height multicol should force 1px tall columns");
</script>
